Most people don’t know what role catalytic distillation plays in the petrochemical industry!

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Reaction distillation is one of the coupled separation and reaction techniques in chemical engineering; it represents a relatively advanced technology in this field. Reaction distillation refers to a chemical production process in which separation and reaction take place simultaneously within the same tower. Catalytic distillation technology is the reactive distillation technology that uses catalysts. In the early 1980s, catalytic distillation technology was developed. The rational and scientific use of this technology in petrochemical production processes allows the reaction products to be removed as quickly as possible. Additionally, distillation can make use of the heat generated during the reaction, which helps to reduce energy consumption in production and thus lowers equipment investment, thereby improving the economic efficiency of petrochemical enterprises. ◆◆◆ I. The role of catalytic distillation technology in etherification reactions: In the petroleum chemical industry, it is necessary to produce methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and diol ethers. In the 1980s, researchers used mixed tetrahydrocarbons and methanol as basic raw materials, and employed cation exchange technology and catalytic distillation to successfully synthesize MTBE. After this technology was widely adopted, the production capacity of petrochemical enterprises was greatly improved. Following catalytic distillation and cracking treatment, the production of isobutylene in China became domestically feasible, saving oil companies substantial production costs; this technology was primarily based on the patented production methods used in the United States for MTBE. During its use, MEBE causes severe pollution to the ecological environment, particularly leading to serious contamination of water resources. To effectively address this issue, ETBE was successfully synthesized by improving the MTBE production process. There have been significant improvements in terms of harmony, vapor pressure, and octane rating, and its ability to cause environmental damage is low, which meets **environmental protection policies**. With the rapid development of the automotive industry, there is an increasing use of ethylene glycol ethers in the solvents for electrophoretic paints. However, these substances pose a serious threat to human health, and in severe cases can even lead to cancer. To reduce the use of ethylene glycol ethers, the application of catalytic distillation in batch reactor reactions can effectively improve the yield of by-products and increase the yield of the desired product, thereby yielding propylene glycol ethers with lower hazards to replace ethylene glycol ethers. In the etherification reaction, the use of catalytic distillation technology not only helps to improve a company’s production capacity effectively, but also reduces environmental pollution and prevents harm to human health; therefore, its application should be promoted in petrochemical production. ◆◆◆ II. The role of catalytic distillation technology in alkylation reactions 1. Production of isopropylbenzene. Among the most basic raw materials in organic chemistry, isopropylbenzene is a very important one; its main uses are in the production of propylene and phenol. In the mid-1980s, an American company developed catalytic distillation technology for the production of isopropylbenzene from propylene and benzene, and pilot tests were also carried out ； By the end of the 20th century, fiber and chemical companies in Taiwan built plants with a capacity of 270 kt/a using catalytic distillation technology. Propylene and benzene are fed into the upper and middle sections of the alkylation reactor; the lower section of the reactor serves as the distillation section, while the upper section functions as the reaction section. The packing in the reaction section consists of catalysts that have been specially arranged and packaged. Vapor-phase propylene and liquid-phase benzene are introduced simultaneously onto the surface of the catalyst, in a molar ratio of 1:10 between benzene and propylene; this approach effectively prevents the formation of polyisopropylbenzene, thereby allowing for a significant increase in the conversion rate of the main reaction. Formation of 2-ethylbenzene. Ethylbenzene is also a very important chemical raw material. China produces over 2 Mt/a of dry gas as a by-product of catalytic cracking, yet the ethylene generated cannot be fully utilized. Ethylbenzene is produced by the alkylation of refinery catalytic cracking gas and benzene, and industrial production of this compound was actually achieved in the early 1990s. Subsequently, a method was successfully developed for synthesizing ethylbenzene using pure ethylene as a raw material and novel molecular sieve catalysts. 3 Synthesis of straight-chain alkylbenzenes. In the production of anionic surfactants such as alkylbenzene sulfonates, linear alkylbenzenes are the primary material used. At the current stage, hydrofluoric acid remains the primary catalyst used in industrial production, and this production method may pose significant safety risks as well as environmental pollution problems. If the slurry-bed catalyst distillation process is chosen for the production of linear alkylbenzenes, the resulting product will contain fewer impurities, allowing it to be used as a raw material for the manufacture of high-quality detergents. Synthesis of 4-methyl acetal. In the production of high-quality general-purpose engineering plastic, polyoxymethylene resin, the synthesis of methylal is a very important step. Using solid acid catalyst distillation technology, formaldehyde and methanol can be condensed to produce methylal with a relatively high concentration, and the conversion rate of formaldehyde is very high. ◆◆◆ III. The role of catalytic distillation technology in isomerization reactions Isoparaffins are very important components in diesel, lubricating oils, aviation kerosene, and gasoline. At present, alkyl isomerization has become a highly developed technique, and the rational and effective use of catalytic distillation technology can significantly increase the yield of isoparaffins. Complete isomerization technology is one of the more commonly used techniques; molecular sieve adsorption separation and isomerization together constitute the complete isomerization production process. ◆◆◆ IV. The role of catalytic distillation technology in esterification reactions: When petrochemical companies produce propylene glycol monoalkyl ether carboxylates using traditional methods, it is difficult to control the production process. In such processes, propylene glycol ethers and acetic acid in the raw materials do not react completely, and these substances remain in the aqueous phase at the top of the tower. After production is completed, certain equipment must also be installed in the production line to recover the subsequent reactants. In this process, not only is a large amount of raw material wasted, but it also increases production costs and makes control more difficult. By employing catalytic distillation technology during the production process, it is possible to control the temperature and pressure during the reaction. The oil phase at the top of the tower is recycled, which reduces the difficulty of control and ensures that the propylene glycol ethers and acetic acid in the raw materials undergo complete reaction; no residual raw materials remain at the top of the tower, thereby eliminating the need for separate recovery operations. This improves production efficiency and reduces production costs. In the production of methyl methacrylate, catalytic distillation technology makes use of the properties of large-pore, strongly acidic cation exchange resins as catalysts. The corresponding reactors are extended to maintain a temperature of 80 to 100 degrees Celsius. The azeotropes formed as a result of the esterification reaction in the reactor emerge as vapor, which allows the reaction to continue once the equilibrium in the reactor is disrupted. Thanks to the catalyst, the yield of methyl methacrylate is greatly increased, and temperature control is possible to enable selective production. At the same time, no other solvents are required during the production process, which simplifies the subsequent control of the reaction and helps save energy. Xiao Qi’s summary: In the petrochemical industry, the use of catalytic distillation technology during production processes enables more efficient carrying out of etherification, alkylation, isomerization, and esterification reactions. This improves production efficiency, reduces the need for various additives in the production process, and helps to conserve natural resources ； At the same time, during the production process, the manufacturing procedures were simplified, enabling effective control over the production process ； The number of subsequent recovery operations in some production processes has been reduced, which **has lowered the costs involved and thus improved the economic efficiency of the enterprises.